Dec. 30th, 2004

* The biggest problem with using hydrogen with an airship is the flammability. Could hydrogen be made non-flammable (or non-flammable enough) by making it into a foam? Maybe by using fluorocarbons?

* Could you make a autogyro with giant, inflatable helium filled wings? Perhaps using tensairity principles to make the blades rigid enough? What about a helium filled flying wing? Powered parachute?

* Current designs for seasteads call for monolithic ferrocement construction. However, ferrocement is very heavy, and it would be difficult to build the seastead offshore, then transport it to the ocean. Could a variant of panelized construction be used? Maybe design the pillar as an ocatagon, and use tiled interlocking panels. Could they be made water tight? What about expansion/contraction due to thermal differentials?

* What about using pillowdome technology to build a large rigid hexagonal geodesic sphere? How were the pillowdomes made watertight? How much aluminum/tefzel would be required to build a structure sufficient for carrying a family of 4+4? How would such a structure respond to high winds? How could it be safely tethered? Are "airsteads" practical?

* What about using water ballast for seasteads instead of concrete?

* What about using a photovoltaic fabric to cover the surface of the airship? The electricity generated could be used to form hydrogen, and thus keep the sphere perpetually afloat. What are the current limitations of photovoltaic fabrics?

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Comments:

The biggest problem with using hydrogen with an airship is the flammability. Could hydrogen be made non-flammable (or non-flammable enough) by making it into a foam? Maybe by using fluorocarbons?

Well, it still wouldn't get you much over just using helium. Heck, using vacuum-filled unobtanium balloons gets you something like 6% more bouyancy than using helium.

Could you make a autogyro with giant, inflatable helium filled wings?

Depends. Do you really mean an autogyro, in which the wing is a rotary one? If so, I can't see that it'd be practical: any material strong enough withstand the wing loading in various dimensions is going to be heavy enough that it's gonna kill any benefit you might see from filling it with a bouyant gas. If you're talking about some kind of hybrid, with a free-wheeling rotary wing paired with a fix wing, I still don't see it being useful. The point of an autogyro is that forward motion spins the rotary wing, generating lift. Big helium-filled fixed wings = much drag = little forward motion = little lift from the rotary wing. I could see a rigid or semi-rigid gas-filled lifting body, but not an autogyro.

What are the current limitations of photovoltaic fabrics?

Shitty efficiency. Keep in mind that commercial hydrogen generation involves steam reformation of hydrocarbons, not electrolysis, which requires a great deal of power.

As I wrote in the title, these are mostly notes to myself -- I'm not saying any of these ideas are workable.

With respect to hydrogen foam, I'm not trying to get more lift. Helium's scarce and expensive--the U.S. controls most of the known world reserves. Hydrogen is abundant, and can be manufactured onsite. It can also be used as a fuel source, so the same gas used to provide lift could also be used to power an engine for propulsion. The biggest disadvantage to hydrogen is its flammability.

Photovoltaic fabrics may have shitty efficiency, but airships have a lot of surface area.